Increased environmental awareness has led to more stringent standards and regulations regarding the discharge of effluent from vessels. To comply with these standards various marine sanitation devices have been developed. Systems designed to treat human waste, or "blackwater", must be capable of removing suspended solids, removing dissolved organic solids, and disinfecting the effluent prior to discharge. In addition, a system intended for use aboard ship must satisfy size, efficiency, and reliability constraints without requiring constant monitoring by an operator.
Marine sanitation systems currently in use remove suspended solids from wastewater by such methods as screening, settling, filtering, and flotation. These methods are effective, but they require varying degrees of maintenance and operator control. A common method of removing both suspended and dissolved solids is biological digestion, but this method has not been found satisfactory for shipboard use because of the relatively long treatment times required. Disinfection of the effluent prior to discharge has primarily been accomplished by chlorination. However, chlorination leaves an undesirable chemical residue in the effluent which is often excessive and thus harmful to aquatic life.
Thus, there is a need for a wastewater system suitable for use aboard ship which is neither oversized, complicated, nor costly and does not require an inordinate amount of operator attention or maintenance.